Introduction: Tumefactive Demyelination (TD) is an uncommon paediatric presentation of demyelinating disease and poses a significant diagnostic challenge due to its close clinical and radiological resemblance to intracranial tumours or infarction. Early recognition is crucial to avoid unnecessary invasive procedures and to facilitate timely management. Case presentation: We report a previously healthy 13–year–old boy who presented with acute right sided hemiplegia, preceded by a sudden decline in fine motor function affecting handwriting. There were no other associated symptoms. Baseline blood investigations and cerebrospinal fluid analysis, including Oligoclonal Bands were normal. Contrast–enhanced CT of the brain demonstrated a focal abnormality in the left precentral region, raising suspicion of a tumour or infarction. Subsequent MRI revealed a large left frontal subcortical white matter lesion involving the precentral gyrus, with thin open–ring enhancement, peripheral diffusion restriction, and mild mass effect, consistent with Tumefactive demyelination. He was treated with intravenous methylprednisolone, immunoglobulin followed by a tapering course of oral prednisolone with mycophenolate mofetil and vitamin D supplementation, resulting in significant clinical improvement. Follow up MRI at two months showed marked lesion regression, with no evidence of active demyelination or spinal cord involvement, confirming the diagnosis. Conclusion: This case highlights TD as a rare but important mimic of intracranial tumours, in paediatric practice. Recognition of characteristic MRI features particularly thin open–ring enhancement with the incomplete margin facing the grey matter together with interval imaging following immunomodulatory therapy , is pivotal in preventing misdiagnosis and avoiding unnecessary neurosurgical intervention.